Blow molding method for forming a lightweight plastic bottle

ABSTRACT

A method and apparatus for forming a lightweight plastic bottle having a body and an integral handle includes pre-blowing a tubular parison positioned between partible blow mold sections, closing the blow mold sections to compression mold the handle and blowing the parison to form the body integral with the handle and a line of juncture between the body and the handle.

This is a divisional of copending application(s) Ser. No. 07/594,807filed on Oct. 9, 1990, now U.S. Pat. No. 5,086,937.

BACKGROUND OF THE INVENTION

The present invention relates to an ultra lightweight plastic bottle andto a method and apparatus for forming such bottle. In the utilization ofplastic bottles for packaging, one of the primary objects has alwaysbeen to provide a bottle or other plastic package which utilizes aslittle plastic as possible and still permits the package to reach itsintended market intact in a form which is convenient to use. Althoughattempts have been made to package products in flexible plastic bagsincluding pouches and the so-called bag-in-a-box which has been utilizedfor packaging wine, for packages of 1 quart to 1 gallon in size, suchflexible packaging has seen limited use. The reason for this appears tobe that many of the products packaged in those sizes of containers aredetergents and other common household products and the consumer desiresto have a bottle, preferably one with a handle, for use in packagingsuch products.

More recently, there has appeared on the market a one-liter film plasticpouch marketed under the name "Enviro-Pak" (Trademark of The Procter &Gamble Company) which is used for packaging a fabric softenerconcentrate. Upon opening, the entire contents are intended to be placedin a more rigid plastic or other container.

SUMMARY OF THE INVENTION

The present invention relates to a plastic bottle which has upper andlower portions of sufficient thickness to provide rigidity required fora defined molded shape but which has a greatly reduced thickness in thecentral body portion, for example, a thickness on the order of thatutilized in film, namely, in the range of 0.008 inch.

In one embodiment of the present invention the bottle may have a wallthickness in the center area which is so thin that grasping the bottlein that area will cause the wall in such area to deform to an extentwhich is unacceptable unless supported by some supplementary means. Suchsupplementary supporting means will usually be a label affixed to thecenter area; however, whether labelled or not, when filled with productand sealed, the product contained therein and sealed air of other gas inthe headspace provides the support needed to permit a filled bottle ofthe present invention to stand upright. If labelled, the label may beheat sealed or adhesively affixed but preferably is affixed by in-moldlabelling such as disclosed in U.S. Pat. No. 4,624,722 and 4,636,166(copies enclosed) which are incorporated herein by reference.Preferably, the bottle has a solid handle compression molded integrallywith the upper body portion or shoulder, said body portion or shoulderhaving a greater thickness than the central body portion. Such integralcompression molded handle permits the bottle to be readily grasped andthe contents to be poured therefrom without the risk of prematurelyexpelling the contents. Thus, the thinness of the center area wallportion is such that if a filled bottle is uncapped and grasped in thatarea with a force as needed to lift the bottle, it will deform to suchan extent as to expell some of the liquid out of the neck prior tomoving the bottle to the desired pouring position. The present inventionalso relates to a method and apparatus for forming such bottle in onepiece, with all portions including the handle molded as an integral, insitu molded unit.

Accordingly, it is an object of the present invention to provide aplastic bottle which has upper and lower portions having wallthicknesses sufficiently great to give such portions rigidity capable ofmaintaining their "as-molded" shapes during handling whether empty orfilled and a central portion integral with said upper and lower portionsand having a greatly reduced thickness such as to be incapable ofmaintaining its "as-molded" shape during handling without supplementarysupporting means.

It is a further object of the present invention to provide such a bottlewith an integral handle to facilitate handling and dispensing theproduct therefrom.

It is yet another object of the present invention to provide a methodand apparatus for forming, in one operation, a plastic bottle having ashaped bottom and a shaped upper portion, each having a thicknesscapable of retaining the "as-molded" shape and having a central portionmolded integrally therewith, the thickness of which is greatly reducedfrom that of the upper and lower portions.

It is yet another object of the present invention to provide a methodand apparatus for forming such bottle with an integral solid handle.

It is another object of the present invention to provide such a bottlein combination with a label affixed to said central portion, preferablyby in-mold labelling.

In forming the bottle of the present invention, a tubular parison isextruded from an extrusion die head and, while the parison is in heated,moldable condition but before the blow mold halves are closedtherearound, the parison is pre-blown to expand the parison radially toposition plastic material in an area where it will be enclosed withinthe handle cavity of the blow mold halves in order to compression moldthe handle portion when the blow mold halves close around the parison.The handle and the handle cavity of the mold have a configuration whichcauses the handle to be compression molded therein in solid form. Afterclosing of the blow mold halves and compression molding of the handle,pressurized air is introduced into the parison to form the blownportions of the bottle, including an upper body or shoulder portionadjacent the neck. The handle is formed solid, preferably with anenlarged bead at its outer periphery which extends the full length ofthe handle except the end portions adjoining the upper body or shoulderwhich are of reduced thickness. For those bottles having handles whichare relatively thick in the web areas adjacent the upper body orshoulder, say a thickness greater than 0.050 inches, it is desirablethat such handles be provided with a ribbon or line of reducedthickness, on the order of 0.038 to 0.045 inch, at the line of juncturebetween the handle and shoulder of the bottle in order to preventpressurized air from reaching the interior of the handle during the blowmolding step. The neck portion of the bottle may be formed either byblow molding or injecting molding. If the bottle is labelled by in-moldlabelling, the label is placed in the mold halves prior to their closingaround the parison.

The plastic bottle of the present invention can be formed on a number ofdifferent types of blow molding machines including a wheel-type blowmolding machine, such as described in U.S. Pat. Nos. 4,523,904;4,549,865 and 4,648,831 and on machines in which a portion such as theneck, is injection molded in a partible injection mold which thencarries such injection molded portion and a tubular parison as it isextruded upwardly between partible blow mold halves which are thenclosed therearound and the parison blown therein to form the bottle.Examples of such machines are disclosed in the following U.S. Pat. Nos.3,029,471, 3,019,480 and 3,008,192.

The concept of pre-blowing a parison for various reasons including thatof getting plastic material radially outwardly into alignment with ahandle cavity of a partible blow mold is disclosed in the prior artincluding the following U.S. Pat. Nos. 2,953,817; 3,012,286 and3,983,199.

All of the above patents are incorporated herein by reference.

IN THE DRAWINGS

FIG. 1 is an elevational view of the bottle of the present invention.

FIG. 2 is a top plan view of the bottle shown in FIG. 1.

FIG. 3 is an end view of the bottle shown in FIG. 1.

FIG. 4 is a fragmentary perspective view of the upper portion of thebottle shown in FIG. 1.

FIG. 5 is a sectional view taken through line 5--5 of FIG. 3.

FIG. 6 is a sectional view taken through line 6--6 of FIG. 1.

FIG. 7 is a sectional view taken through line 7--7 of FIG. 1.

FIG. 8 is a sectional view taken through line 8--8 of FIG. 6.

FIG. 9 is a sectional view taken through line 9--9 of FIG. 1.

FIG. 10 is a fragmentary elevational view of the bottle of the presentinvention showing a modified handle configuration.

FIG. 11 is a sectional view taken through line 11--11 of FIG. 10.

FIG. 12 is a sectional view taken through line 12--12 of FIG. 10.

FIG. 13 is a view similar to FIG. 10 showing yet a different handleconfiguration.

FIG. 13A is a sectional view taken through line 13A--13A of FIG. 13.

FIG. 14 is a view similar to FIGS. 10 and 13 showing yet another handleconfiguration.

FIG. 15 is a sectional view taken through line 15--15 of FIG. 14.

FIG. 16 is a fragmentary perspective view of a bottle having stillanother type of handle configuration.

FIG. 17 is a sectional view taken through line 17--17 of FIG. 16.

FIG. 18 is a schematic elevational view showing one type of blow moldingmachine which could be utilized to form the bottle of the presentinvention showing a length of plasticized tubing extending between araised injection mold and an extrusion die head and positioned betweenthe open halves of a blow mold.

FIG. 19 is a view of one-half of the open blow mold of FIG. 18 showingin phantom a length of plasticized tubing positioned between it and theother blow mold half.

FIG. 20 is a sectional view taken in the area shown by line 20--20 ofFIG. 19 after closing the mold halves and blow molding of the bottletherein.

FIG. 21 is a view similar to FIG. 20 in the area shown by line 21--21 ofFIG. 19.

FIG. 22 is a view similar to FIG. 20 in the area shown by line 22--22 ofFIG. 19.

FIG. 23 is a sectional view taken in the area shown by line 23--23 ofFIG. 19 of the handle portion of a newly formed bottle after removalfrom the blow mold but prior to trimming the flash therefrom.

FIGS. 24 and 25 are views similar to FIG. 23 taken in the area shown bylines 24--24 and 25--25, respectively.

FIG. 26 is a elevational view of another type blow molding machine whichmay be utilized in forming the bottle of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1-9, there is provided a bottle generallydesignated by the number 10 having a bottom or base portion 11, a bodyportion 12 extending upwardly from the base portion and a neck or finishportion 13 extending upwardly from the body portion 12 and having anopening 14 through which contents of the bottle may be dispensed. Aledge 15 joins the neck 13 to the body 12. The bottle is preferablyformed of high density polyethylene; however, it could be formed of awide variety of other thermoplastic materials such as polypropylene, lowdensity polyethylene and polyvinyl chloride. As may be seen in thedrawings, there is also provided a handle 16 which is integrally formedwith and extends from the upper body portion 12A (i.e., the shoulder) inan area adjacent the neck 13.

The handle 16 is formed integrally with the body portion 12 and iscompression molded within the handle cavity of a mold as will behereinafter described. The handle 16 has a finger hole opening 17 topermit the bottle 10 to be readily grasped and carried.

Referring to FIGS. 5-8, the body portion 12 has three fairly distinctareas including an upper area 12A which has a target minimum wallthickness in the area of 0.015-0.020 inch and an average wall thicknessof 0.020-0.030 inch. Preferably, that portion of the upper area 12A fromwhich the handle 16 extends has a wall thickness on the order of0.020-0.030 inch.

The body portion 12 also includes a central area 12B which has athickness on the order of 0.008 inch which approximates the thickness ofa flexible film. The thinness of the central area 12B results in thatarea having limited ability to maintain its "as-molded" shape duringhandling when grasped in that area unless there is some additionalsupporting means such as a label affixed to such area or supportresulting from having product and sealed air or other gas in theheadspace. In contrast, the upper and lower areas 12A and 12C havethicknesses providing sufficient strength and rigidity to permit theirhandling without significantly deforming their "as-molded" shapes. Forsome bottles, there may even be a tendency for the upper area 12A andneck 13 of an empty, unsealed bottle 10 to droop at least slightly fromthe axis of the neck as molded. Thus, if the central area 12B is thinenough, it may be incapable of holding the upper portion 12A of the bodyand the handle 16 and neck 12 in the same upright position in whichmolded without some additional supporting means and yet be capable ofcontaining liquid product.

The lower area 12C of the bottle has a greater wall thickness than thecentral area 12B with a target minimum thickness on the order of 0.010to 0.015 inch and an average wall thickness of 0.020 to 0.040 inch.Thus, the upper and lower areas 12A and 12C respectively of the body 12have sufficient rigidity to maintain a shape with normal deformationexpected for a plastic bottle during handling while the central area12B, by virtue of its greatly reduced thickness, lacks any substantialrigidity.

The base 11 has a target minimum thickness of 0.015-0.025 inch with anaverage thickness of 0.020-0.040 inch. Preferably, the base 11 has acentral rib 18 extending laterally across the bottle 10 to provideadditional rigidity in that area.

Referring now to FIGS. 1-4 and 9, the handle 16 extends outwardly fromthe upper area 12A and includes an inner web portion 20 and an outerportion of maximum breadth 21 which encircles the finger hole opening 17and extends on opposite sides of the web portion 20 to a position nearbut spaced from the wall of the upper area 12A. The handle 16 also has aline of juncture 22 of significantly reduced thickness from the webportion 20 joining the handle 16 to the upper area 12A. As can be seenin FIGS. 1-4 and 9, the portion of maximum breadth 21 does not extend tothe body portion upper area 12A but rather is separated from it by thereduced thickness line of juncture 22.

The portion of maximum breadth 21 may have any of a wide variety ofthickness ranges as determined by the desired comfort to the fingers ofthe persons gripping the handle 16 and the desired rigidity of thehandle. While it is preferred that the portion of maximum breadth 21have a greater thickness than the web 20, it could be as thin as the web20 or as thick as 1/4 to 1/2 inch. The thickness of the web 20 in theembodiment of FIGS. 1-4 and 9 is preferably in the range of 0.050 to0.060 inch. The thickness at the line of juncture 22 is in the range of0.038 to 0.045 inch. As will become clearer from the description of themethod and apparatus for forming the bottle of the present invention tobe hereinafter described, the feature of providing the line of juncture22 with thickness in the range of 0.038 to 0.045 inch or less enhancesthe ability to compression mold a solid handle throughout the webportion 20 and portion of maximum breadth 21 and minimizes the chancesof pressurized air from getting into the handle 16 during the blowmolding operation. Thus, if any air or pressurized air became entrappedin the handle 16, that would serve to greatly weaken the structuralintegrity of the handle 16 and its ability to support the bottle beingcarried. Obviously, the area of reduced thickness 22 must havesufficient thickness to provide good support and as pointed out aboveshould be on the order of 0.038 to 0.045 inches.

Referring now to FIGS. 10-17, there are shown several different types ofhandle configurations. Thus, in FIGS. 10-12 there is provided a bottle30 with a body portion 31 having an upper area 31A defining a shoulderterminating in a horizontal ledge 32 from which a neck 33 extends. Thebottle 30 of this embodiment has a handle 34 which extends from thehorizontal ledge 32 adjacent the neck 33 to a point where the slopingshoulder of the upper area 31A flows to an approximately verticalextent. The handle 34 includes (1) a finger hole opening 35 defined by acircular portion of maximum breadth 36 and (2) secondary portions ofmaximum breadth 37 and a pair of web portions 38 on opposite sides ofthe finger hole 35 which are joined to the circular portion of maximumbreadth 36 and to the secondary portions of maximum breadth 37. A lineof juncture 39 joins the web 38 and the tangent of the circular portionof maximum breadth 36 to the upper area 31A of the bottle 30.Preferably, the line of juncture 39 has a thickness which is reducedfrom that of the web 38; however, if the web 38 has a thickness not toexceed approximately 0.045 inch, the line of juncture 39 can be the samethickness. Under no circumstances, however, should the secondaryportions of maximum breadth 37 extend to the wall of the body portionupper area 31A. Thus, there will be a gap between the ends 37' of thesecondary portion of maximum breadth 37 and the wall at the upper area31A of the body portion.

FIG. 13 shows a bottle 40 having a shape somewhat similar to the bottleof FIG. 10 but having a handle 44 with two finger gripping apertures 45.This bottle also has a horizontal ledge 42 and a body portion having anupper area 41A with the handle 44 extending from the horizontal ledge 42to the wall of the body portion upper area 41A. The handle 44 of thisembodiment has two circular portions of maximum breadth 46 and asecondary portion of maximum breadth 47. Four web sections 48 and a lineof juncture 49 join the handle 44 to the body portion upper area 41A.The secondary portion of maximum breadth 47 terminates before reachingthe wall of the upper portion 41A with the result that the ends 47' arespaced from the wall of the upper area 41A.

Referring now to FIGS. 14 and 15, there is shown another embodiment inwhich there is provided a bottle 50 having a body portion with an upperarea 51A, a horizontal ledge 52 and a neck 53. A handle 54 is providedhaving an elongated hand opening 55 extending from the ledge 52 to apoint on the body portion upper area 51A. Under this embodiment, thereis provided a first portion of maximum breadth 56 around the handopening 55 and a secondary portion of maximum breadth 57 extending froma point near the ledge 52 to a point near the body portion upper area51A. The secondary portion 57 has ends 57' which are spaced from thewall of the upper area 51A. A web 58 extends between the first andsecond areas of maximum breadth 56 and 57 and is joined to the bodyportion upper area 51A at a line of juncture 59 of reduced thickness.

Referring now to FIGS. 16 and 17, there is shown a bottle 60 with ahandle 64 similar to that of the bottle shown in the embodiment of FIGS.14 and 15 except that it has a web portion 98 which tapers to a minimumthickness at its juncture 69 with the body portion upper area 61A. Thus,it has first area of maximum breadth 66 around the hand opening 65 and asecondary portion of maximum breadth 67 extending from opposite ends 67'near but spaced from the body portion upper area 61A. As can be seen inFIG. 16, the secondary portion of maximum breadth 67 does not extend tothe side wall of the body portion upper area 61A but rather simply fadesout at the opposite ends 67', tapering to the minimum thickness at theline of juncture 69.

Referring now to FIGS. 18-25, there will be described one method andapparatus for molding the bottle of the present invention. This is amachine operating according to the principles described in U.S. Pat.Nos. 2,804,654 and 3,019,480. The apparatus includes an extrusion die 70having a die head 71 with an annular orifice 72 through which heated andplasticized material may be extruded, Positioned above the die head 71is an injection head 73 having an injection mold 74 mounted thereon. Theinjection head 73 is supported by means not shown for raising andlowering it and the injection mold 74 from a position at which theinjection mold 74 is firmly in engagement with the die head 71, to araised position. The injection mold 74 has a cavity (not shown) alignedto receive plastic material from the orifice 72 of the die head when theinjection head is in the lowered, engaged position. Such constructionpermits heated and plasticized thermoplastic material to be injectionmolded from the die head 71 through its orifice 72 and into the moldcavity of the injection mold 74. Upon completion of such injectionmolding step, the injection head 73 is raised as plasticized materialcontinues to be expelled through the orifice 72 in the form of a tubularparison 75 which is supported and carried upwardly by the injection mold74.

A pair of partible mold halves 76 are mounted on opposite sides of thepath followed by the injection head 73 in a position to close around thetubular parison 75 at the appropriate stage in the cycle when theinjection head 73 is in the raised position. The injection head 73includes a passageway 68 which extends through the injection mold 74 forintroducing pressurized air into the tubular parison. In order tocompression mold the handle portion, for example, the handle 16 in theembodiment of the bottle shown in FIGS. 1-4, it is desirable tointroduce such pressurized air into the tubular parison 75 in stages,the first of which is prior to closing the blow mold halves 76 aroundsuch tubular parison 75. The introduction of pressurized air into theparison 75 at a selected time prior to closing the mold halves 76 servesto pre-blow and, thus, expand a selected portion 75A of the parison to aradial extent such that it will be enclosed within the handle cavity ofthe blow mold halves 76 when they close. As previously mentioned theconcept of pre-blowing a parison is disclosed in U.S. Pat. Nos.2,953,817, 3,012,286 and 3,983,199.

The mold halves 76 are provided with mating surfaces 77 which contactone another when the mold halves 76 are in the closed position. Cut intoeach of the mold halves 76 are (1) a blow cavity 78 conforming to thedesired configuration of the bottle, body and neck portion when the moldhalves 76 are closed, (2) a handle cavity 79, (3) an upper waste cavity80 at the top and (4) a lower waste cavity 81 at the bottom whichprovide recesses into which excess plastic may flow upon closing of theblow mold halves 76 around the tubular parison 75. Following closing ofthe blow mold halves 76, pressurized air is introduced through thepassageway 68 and into the upper end of the tubular parison 75 to expandthat portion of the parison 75 captured within the closed mold halves 76into conformity with the cavity 78. As previously mentioned, the closingof the mold halves 76 compression molds the handle in the handle cavity.As can be seen in FIG. 18, the portion of the waste cavity 80 above thetop of the blow cavity is recessed deeper (i.e., farther away from themating surfaces 77) so that, upon closing of the mold halves 76, therewill still be an open path for pressurized air to flow from thepassageway 68 to the mold cavity 78.

As can be seen in FIGS. 19 and 20, in forming a bottle having aconfiguration of the bottle 10 shown in FIGS. 1-4, upon completion ofthe blow molding there will be formed the neck 13, the handle 16 andflash or waste material 89 which will be trimmed in a separate trimmingoperation. Flash 89A is also formed in the finger hole opening 17 of thehandle 16. Additionally, the portion of the mold halves 76 forming theline of juncture 22 of reduced thickness are contoured toward oneanother as at 85 as shown in FIG. 22.

FIGS. 23, 24 and 25 show the respective portions of the bottle as moldedprior to trimming but after removal from the mold. As noted particularlyat FIG. 25, the wall forming the body portion 12 at the upper area 12Aat the line of juncture 22 has a tendency to be pushed into the handlearea as illustrated by the dimple 86. As will be appreciated, if theline of juncture 22 has a thickness of greater than about 0.045 inch,the pressurized air could push into the handle cavity area creating anundesirable air bubble therein.

In operation, the injection head 73 is initially lowered to a positionat which the injection mold 74 engages the die head 71 with an openingto the injection cavity aligned with the orifice 72 of the die head 71.Plasticized material is then injection molded into the injection mold 74and the injection head 73 is then lifted as plasticized materialcontinues to be expelled or extruded from the die orifice 72 in the formof a tubular parison 75. At a point in time during such lifting, a smallamount of pressurized fluid is introduced therein to pre-blow andthereby expand an area 75A which is to be aligned with the handle cavity79 of the mold halves 76 in which the handle 16 is to be compressionmolded. Following completion of the extrusion step and raising of theinjection mold 74 above the blow mold halves 76, the blow mold halves 76are caused to close around the tubular parison 75 compression moldingthe plastic material in the pre-blown area 75A in the handle cavity 79.Thereafter, pressurized air is introduced through passageway 68 toexpand the portion of the parison 75 contained within the blow cavity 78into conformity with such blow cavity. Following this step the blow moldhalves 76 are opened, the bottle with the flash thereon removed from themold cavity 78 and injection head 73 returned to engagement with the diehead 71 for beginning of a new cycle. The bottle then has the flash 89and 89A trimmed therefrom to form the finished article.

Referring now to FIG. 26, the wheel-type blow molding machine which maybe utilized for forming the bottle of the present invention comprises aframe 120 in which a shaft 121 is mounted for rotation about ahorizontal axis. A wheel plate 122 is mounted on the shaft 121 forrotation with the shaft 121 and supports a plurality ofcircumferentially spaced slide assemblies 123. A hub 125 is also mountedon the shaft for rotation with the shaft and has a plurality ofcircumferentially spaced mold supporting surfaces 126 corresponding innumber to the number of slide assemblies 123.

Each slide assembly 123 supports a first section or part 127 of mold andthe corresponding surface 126 of the hub 125 supports the second section128 of a mold. Each slide assembly 123 is adapted to move the moldsection 127 toward and away from the other mold section 128 to closeabout a heated parison 105 emanating from an extruder head 129 so thatthe parison can be blown to the shape of the mold cavity defined by themold sections 127, 128 as the wheel rotates. The parison 105 is providedfrom the head 129 of an extruder in the two o'clock position as shown inFIG. 26.

Wheel plate 122 is rotated by a gear 130 driven by a motor 131 andmeshing with a gear 132 on the periphery of the wheel plate. Each slideassembly 123 includes a cam follower 133 which engages a fixed arcuatecam 134 on the frame 120 to move mold section 127 toward and away frommold section 128. A second cam follower 135 on each slide assembly 123engages a second fixed cam 136 on frame 120 to hold the mold sections127, 128 in closed position. Second cam 136 extends generally from thethree o'clock position to the nine o'clock position.

An air valve 142 is provided on each slide assembly 123 and is actuatedby an actuator 143 along the path of the molds that functions to turnthe blow air on for blowing the article and another actuator 144 isprovided along the path to function to turn the air valve 142 offcutting off the flow of blow air to the parison enclosed in the moldsections 127, 128. This type of blow molding machine is described ingreater detail in the following U.S. Patents which are assigned to theassignee of the present invention and are incorporated herein byreference: U.S. Pat. Nos. 4,523,904; 4,549,865 and 4,648,831.

In addition, means are provided for pre-blowing the parison 105 after itemanates from the extruder head and before it is enclosed within themold sections 127, 128. As in the previous machine, the purpose of thepre-blowing step is to get a portion of the plastic material alignedwith the handle cavity of the blow mold sections 127, 128 where it willbe compression molded in such handle cavity as the blow mold sections127, 128 close therearound. In order to accomplish such pre-blowing, theextruder head 129 is provided with a central air passageway opening tothe interior of parison 105 as it is extruded.

In operation the plastic material is continuously extruded from the head129 of the extruder in the form of a tubular parison 105 and flowsdownwardly between the mold sections 127, 128. As the wheel platecontinues to rotate, the mold sections 127, 128 are brought togetherpinching the plastic material and air is supplied to the interior of thetubular parison to blow the article in a manner well known in the art.

Prior to closing the mold sections 127, 128 a puff of pressurized air isintroduced into the parison 105. The timing and amount of pressurizedair introduced in the pre-blowing step prior to closing the moldsections 127, 128 is programmed to cause plastic material to be expandedto a position where it can be compression molded in the handle cavity asthe mold sections 127, 128 close therearound. Thereafter, pressurizedair is introduced through a needle to expand the parison in the cavityof the mold sections 127, 128. As the article reaches the position whenthe blow mold is open (twelve o'clock position as viewed in FIG. 26) anejector ejects the bottles onto a conveyor.

I claim:
 1. A method for blow molding a plastic bottle having a baseincluding a bottom intended to rest upon a supporting surface, anintegral body portion extending upwardly from said base and including acentral area and a shoulder portion above said central area, anddispensing means extending from said shoulder portion, said shoulderportion having an integral solid handle extending therefrom, said handlehaving a web of predetermined thickness and an enlarged bead at theouter periphery of said web opposite said shoulder portion, said methodcomprising the steps of:(a) providing a tubular parison in heatedmoldable condition; (b) positioning said parison between partible blowmold sections having a cavity with (i) a first portion defining theshape of said bottom, body portion and dispensing means and (ii) asecond portion defining the shape of the handle communicating with saidfirst portion throughout a line of juncture; (c) introducing lowpressure gas into said parison to pre-blow (i) that portion of saidparison intended to form said integral handle to a radial extent to becaptured within said second portion upon closing of said mold sectionsand that, upon expanding in said blow mold cavity, said shoulder portionwill have a target minimum thickness of 0.015 inch and a target averagethickness between 0.020 inch and 0.030 inch and (ii) that portion ofsaid parison intended to form said central area to cause such parisonportion to thin to an extent such that, upon expanding in said blow moldcavity, said central area will have a target maximum thickness of 0.012inch; (d) thereafter closing said partible blow mold sections aroundsaid pre-blown parison to enclose a major portion thereof in said cavityfirst portion while compression molding a minor portion in said cavitysecond portion to form the solid handle; and, (e) introducing highpressure gas into that portion of the mold enclosed parison lying withinsaid cavity first portion while preventing said high pressure gas fromentering that portion of said parison enclosed in said cavity secondportion by pinching said parison at the line of juncture between saidcavity first portion and said cavity second portion such that thecompression molded handle formed at said line of juncture is thinnerthan the portion of the web of said handle adjacent thereto, andpinching said parison at the opposite ends of said bead adjacent saidshoulder prior to introducing said high pressure gas, thereby formingthe bottom, body and shoulder portions integral with said solid handle,said solid handle extending from said shoulder portion along the line ofjuncture, said handle having, at said opposite ends, areas of reducedthickness between said enlarged bead and said shoulder portion said areaof reduced thickness being thinner than said predetermined thickness.